Corneal Expression and Function of Slurp1

描述(申请人提供)：虽然分泌型Ly6/尿激酶型纤溶酶原激活剂受体(UPAR)相关蛋白-1(Slurp1)是角膜中表达最丰富的蛋白之一，并分泌到泪膜中，但其在眼表的生物学功能尚不清楚。在这个项目中，我们测试了核心假设，即Slurp1是一种关键的免疫调节分子，它抑制眼表炎症，并在促炎条件下下调。这一假说得到了我们激动人心的初步数据的支持，这些数据表明：(I)当小鼠眼睑首次暴露于环境时，Slurp1的表达增加；(Ii)在细菌脂多糖(LPS)注射或单纯疱疹病毒1型(HSV-1)感染合并中性粒细胞渗透的24小时内，Slurp1的表达被抑制；(Iii)在发炎的Klf4条件无效(Klf4CN)角膜中，Slurp1的表达减少，以及(Iv)促炎症白介素IL-4和IL-13抑制。更重要的是，(A)SLurp1的过度表达阻碍了腺病毒角膜炎中性粒细胞的流入，以及(B)Slurp1与uPAR配体uPA结合，提示SLurp1通过竞争结合uPAR配体来抑制炎症。我们将通过追求三个具体目标来检验我们的假设。在目标1中，我们将建立Slurp1的角膜功能。我们将通过监测Slurp1在几个不同的实验模型中的表达来确定Slurp1的表达减少是否是角膜炎症的共同主题。通过利用分子方法减少或增加小鼠角膜中Slurp1的表达，我们将确定这些变化分别是增强还是减轻炎症。在目标2中，我们将研究Slurp1功能的分子机制。我们将确定Slurp1是否与uPAR竞争与其配体uPA、Vitronectin和整合素的结合，从而导致中性粒细胞迁移减少。在目标3中，我们将询问调控SLurp1在健康和炎症角膜中表达的分子事件。我们将确定Kruppel样转录因子-4(KLF4)是否控制眼皮张开时Slurp1表达的增加，以及在促炎条件下，在不同刺激下产生的活性氧物种是否抑制Slurp1。该项目基于Slurp1是一种分子开关的新概念，该分子开关在正常水平存在时抑制慢性炎症，在促炎条件下下调，将产生与眼表健康和疾病相关的有价值的新信息。它创新性地利用了我们独特的小鼠模型，扩展了基因调控和先天性免疫反应之间的接口知识，并建立了解释眼表炎症调控的新范式。预期的结果将为眼表炎症性疾病的治疗干预确定一个新的靶点。

DESCRIPTION (provided by applicant): Though the secreted Ly6/urokinase type plasminogen activator receptor (uPAR) related protein-1 (Slurp1) is one of the most abundantly expressed proteins in the cornea and is secreted into the tear film, its biological function in the ocular surface is unknown. In this project, we test the central hypothesis that Slurp1 is a key immunomodulatory molecule that suppresses inflammation at the ocular surface and is downregulated in pro-inflammatory conditions. This hypothesis is supported by our exciting preliminary data demonstrating that Slurp1 expression is (i) increased upon mouse eyelid opening when the cornea is first exposed to the environment, (ii) abrogated within 24h of bacterial lipopolysaccharide (LPS) injection or Herpes Simplex Virus type-1 (HSV-1) infection concurrent with neutrophil infiltration, (iii) decreased in the inflamed Klf4-conditional null (Klf4CN) corneas, and (iv) suppressed by pro-inflammatory interleukins IL-4 and IL-13. More importantly, (a) over-expression of Slurp1 hindered the neutrophil influx in adenoviral keratitis and (b) Slurp1 bound the uPAR ligand uPA, suggesting that Slurp1 inhibits inflammation by competitive binding of UPAR ligands. We will test our hypothesis by pursuing three Specific Aims. In Aim 1, we will establish the corneal function of Slurp1. We will determine whether reduced expression of Slurp1 is a common theme in corneal inflammation by monitoring its expression in several different experimental models. By utilizing molecular approaches to decrease or increase mouse corneal expression of Slurp1, we will determine whether these changes augment or mitigate inflammation respectively. In Aim 2, we will examine the molecular mechanisms underlying Slurp1 functions. We will determine whether Slurp1 competes with uPAR for binding to its ligands uPA, vitronectin, and integrins, resulting in decreased neutrophil migration. In Aim 3, we will interrogate the molecular events governing regulation of Slurp1 expression in healthy and inflamed corneas. We will determine if Kruppel-like transcription factor-4 (Klf4) governs the increased expression of Slurp1 upon eyelid opening, and reactive oxygen species produced in response to different stimuli suppress Slurp1 in pro-inflammatory conditions. This project, based on the novel idea that Slurp1 is a molecular switch that suppresses chronic inflammation when present in normal levels and is downregulated in pro-inflammatory conditions will generate valuable new information related to ocular surface health and disease. It makes innovative use of our unique mouse models to expand knowledge of the interface between gene regulation and innate immune response and establishes a new paradigm explaining regulation of inflammation at the ocular surface. The anticipated outcomes will define a novel target for therapeutic intervention in managing inflammatory disorders of the ocular surface.